Many production methods of olefin polymers by using metallocene complexes have already been reported. For example, JP-A 58-19309 disclosed a method of producing olefin polymers using a metallocene complex and aluminoxane. However, such a method, in which olefin polymerization is carried out catalytically by using bis(cyclopentadienyl)zirconium dichloride and methylaluminoxane, had a problem of the low molecular weight of the obtained olefin polymer. To resolve the problem, JP-A 9-87313 disclosed polymerization using dimethylsilyl(tetramethylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride. In such polymerization, the catalytic activity is high, but there is still a need for further improvement in the molecular weights of polymers to be obtained.